Monitoring changes in fat-free mass in HIV-positive men with hypotestosteronemia and AIDS wasting syndrome treated with gonadal hormone replacement therapy

Objective: To compare methods for assessing changes in body composition dur ing gonadal hormone replacement therapy in a group of HIV-positive men with AIDS wasting syndrome. Design: The study included a 21-day, double-blind, randomized, placebo-cont rolled inpatient intervention and a 12-week open-label intervention. The in patient intervention included 18 men who were confined to a metabolic ward. Days 1-7 comprised weight stabilization and body composition measures foll owed by 14 days of nandrolone decanoate at either 65 or 195 mg weekly, or p lacebo, and repeat testing. The open-label intervention comprised 12 weeks of 200 mg nandrolone decanoate fortnightly with measurements of fat-free ma ss at 6 and 12 weeks. Methods: The inpatient intervention measured nitrogen balance from 24 h uri ne and fecal collections and fat-free mass by dual energy x-ray absorptiome try (DEXA), bioimpedance spectroscopy (BIS) and D2O dilution. Nitrogen bala nce was calculated as the difference between dietary intake and urinary and fecal nitrogen excretion. Nitrogen was converted to fat-free mass using th e constant of 32.5 g. Repeated measures analysis of variance was used to de termine which methods were significantly different from the reference nitro gen balance technique. Results: Nitrogen accretion of lean tissue was 0.55 and 0.85 kg weekly for low and high-dose groups, respectively. Estimated nitrogen retention during the open-label study was 0.42 kg weekly. Body weight increased with the es timated lean tissue accretion. DEXA, BIS and D2O methods demonstrated impro vements in fat-free mass, although the BIS estimate of fat-free mass most c losely matched the results of the nitrogen retention method. Conclusion: DEXA, BIS and D2O techniques demonstrated increases in fat-free mass. The BIS method is less costly, more convenient to use, and had resul ts that more closely matched those from nitrogen balance and retention meth ods. BIS may be the preferred method to monitor changes in fat-free mass in AIDS patients and patients with malnutrition. (C) 1999 Lippincott Williams & Wilkins.